The present invention relates to an engine sound processing system that processes an engine sound of a vehicle (automobile) to reproduce the processed engine sound in an interior of the vehicle.
In the related art, the quiet is required of the interior of the vehicle. In particular, as with the engine sound, such a design is adopted that the engine sound does not escape into the interior of the vehicle to the utmost, by interposing the thick noise insulation material between the engine room and the interior of the vehicle, or the like.
However, it is impossible to say that the interior space of the vehicle in the above high quiet is always the most comfortable driving circumstances for the passenger of the vehicle. In other words, in some cases the driver as the driving fan, or the like feels more comfortable in the situation that such driver can hear the moderate engine sound in the interior of the vehicle as the driving circumstances.
In order to realize the taste of such driving fan, the systems for producing artificially the engine sound in the quiet interior of the vehicle were proposed.
As such system, for example, there were the system for capable of sounding the engine sound while emphasizing a part of the frequency band by generating the sinusoidal or pulse sound, which agrees with the number of revolution of the engine (which synchronizes with the engine sound), to emit into the interior of the vehicle and then adding such sinusoidal or pulse sound to the engine sound that actually escapes into the interior of the vehicle (e.g., see Patent Literature 1, Patent Literature 2), the system for sounding a desired engine sound in the interior of the vehicle by recording a desired engine sound previously and then reproducing this recorded engine sound in response to the number of revolution of the engine (e.g., see Patent Literature 3), and others.    Patent Literature 1: JP-A-5-80790    Patent Literature 2: JP-A-2000-172281    Patent Literature 3: JP-A-7-302093
However, the systems set forth in Patent Literatures 1, 2, 3 also generates another sound that is different from the actual engine sound of the vehicle. Therefore, even if the driving conditions are sensed by using other types of sensors, the sound on which the actual engine sound is reflected exactly in response to the driving conditions cannot be always produced.